The space shuttle Discovery has launched from Kennedy Space Center on a two-week mission to the International Space Station. VOA's Brian Wagner reports the seven astronauts on Discovery will deliver a new module to expand the size of the international orbiter.

Light rain showers cleared just hours before the late morning launch of Discovery from the Kennedy Space Center in Florida.

NASA spokesman George Diller monitored the launch sequence of Discovery, which carried seven astronauts and the Harmony module toward the International Space Station.

DILLER: "We have a go for main engine start. T-minus five, four, three, two, one. Booster ignition and liftoff of Discovery, hoisting Harmony to the heavens and opening new gateways for international science. Discovery has cleared the tower."

Earlier, NASA officials said they were monitoring a buildup of ice on a pipe that sends super-cold liquid hydrogen from the external fuel tank to the shuttle's main engines. Engineers said the ice was a possible concern, because it could cause debris to break off during launch and collide with the shuttle.

Foam debris caused damage to the wing of shuttle Columbia in 2003, which caused the orbiter to break up during re-entry, killing all seven astronauts on board. The shuttle Endeavour also was damaged by foam debris during launch in August, but landed safely.

Discovery's commander Pamela Melroy is leading the seven-member crew on what officials say will be one of the most difficult missions in the shuttle program's history. Astronauts are to perform five spacewalks to attach the new module to the International Space Station and practice shuttle repair techniques.

The Italian-built Harmony module is one of several that international partners plan to install to double the interior capacity of the station for astronauts to live and work in space. A European-built laboratory is to be delivered to the station as early as December.